Saliva may detect predictors of mild cognitive impairment, Alzheimer's disease

Metabolomics analyses can provide clinical discrimination, biological pathway information and predict associations between biomarkers and cognition among individuals with Alzheimer’s disease, according to data presented at the Alzheimer’s Association International Conference.

“Metabolomics is a global approach to detecting perturbations in metabolic pathways that can reflect early and subtle disease-related changes in the central nervous system. The metabolome, the end product of gene-environment interactions, can characterize and discriminate metabolic signatures of Alzheimer’s disease and mild cognitive impairment,” study researcher Shraddha Sapkota, MSc, of the University of Alberta in Edmonton, Canada, and colleagues wrote.

Researchers collected salivary specimens, clinical classifications and cognitive data for 35 individuals with normal cognitive aging (mean age, 69.94 years), 25 individuals with mild cognitive impairment (mean age, 70.4 years) and 22 with Alzheimer’s disease (mean age, 77.09 years). To identify metabolite biomarkers, researchers used 13C/12C isotope dansylation labeling technique and liquid chromatography-mass spectrometry.

Orthogonal partial least squares discriminant analyses indicated clear discrimination between all groups and volcano plots identified top discriminant metabolites.

Researchers noted a pattern between predictably directional metabolite and cognition. Individuals with mild cognitive impairment exhibited an upregulated metabolite, while another metabolite (Trp Glu; Glu Trp) was upregulated among individuals with Alzheimer’s disease. Higher levels of these metabolites predicted worse episodic memory performance when analyzed as biomarkers among cognitively normal study participants.

Upregulation of the metabolite Tyr-Asn-Ser was observed among individuals with Alzheimer’s disease, and higher levels predicted slower neurocognitive speed among these study participants.

“Saliva is easily obtained, safe and affordable, and has promising potential for predicting and tracking cognitive decline, but we’re in the very early stages of this work and much more research is needed,” Sapkota said in a press release. “Equally important is the possibility of using saliva to find targets for treatment to address the metabolic component of Alzheimer's, which is still not well understood. This study brings us closer to solving that mystery.” – by Amanda Oldt

Reference:

Sapkota S, et al. Metabolomics Analyses of Salivary Samples Discriminate Normal Aging, Mild Cognitive Impairment, and Alzheimer’s Disease Groups and Produce Biomarkers Predictive of Neurocognitive Performance. Presented at: Alzheimer’s Association International Conference; July 18-23, 2015; Washington, D.C.

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